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1467 lines (1282 loc) · 57.4 KB
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/*
* Copyright (C) 2008-2024 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "ExecutableAllocator.h"
#if ENABLE(JIT)
#include "ExecutableAllocationFuzz.h"
#include "JITOperationValidation.h"
#include "LinkBuffer.h"
#include <wtf/ByteOrder.h>
#include <wtf/CryptographicallyRandomNumber.h>
#include <wtf/FastBitVector.h>
#include <wtf/FileSystem.h>
#include <wtf/FixedVector.h>
#include <wtf/IterationStatus.h>
#include <wtf/MallocSpan.h>
#include <wtf/PageReservation.h>
#include <wtf/ProcessID.h>
#include <wtf/RedBlackTree.h>
#include <wtf/Scope.h>
#include <wtf/SequesteredMalloc.h>
#include <wtf/SystemTracing.h>
#include <wtf/TZoneMallocInlines.h>
#include <wtf/UUID.h>
#include <wtf/WorkQueue.h>
#if ENABLE(LIBPAS_JIT_HEAP)
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
#include <bmalloc/jit_heap.h>
#include <bmalloc/jit_heap_config.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
#else
#include <wtf/MetaAllocator.h>
#endif
#if HAVE(IOS_JIT_RESTRICTIONS) || HAVE(MAC_JIT_RESTRICTIONS)
#include <wtf/cocoa/Entitlements.h>
#endif
#if OS(DARWIN)
#include <fcntl.h>
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <wtf/spi/cocoa/MachVMSPI.h>
#endif
#if USE(INLINE_JIT_PERMISSIONS_API)
#include <wtf/darwin/WeakLinking.h>
WTF_WEAK_LINK_FORCE_IMPORT(be_memory_inline_jit_restrict_with_witness_supported);
#endif
namespace JSC {
using namespace WTF;
#if OS(DARWIN) && CPU(ARM64)
// We already rely on page size being CeilingOnPageSize elsewhere (e.g. MarkedBlock).
// Just use the constexpr CeilingOnPageSize for better efficiency.
static inline constexpr size_t executablePageSize() { return CeilingOnPageSize; }
#else
static inline size_t executablePageSize() { return WTF::pageSize(); }
#endif
#if ENABLE(LIBPAS_JIT_HEAP)
static constexpr size_t minimumPoolSizeForSegregatedHeap = 256 * MB;
#endif
#if defined(FIXED_EXECUTABLE_MEMORY_POOL_SIZE_IN_MB) && FIXED_EXECUTABLE_MEMORY_POOL_SIZE_IN_MB > 0
static constexpr size_t fixedExecutableMemoryPoolSize = FIXED_EXECUTABLE_MEMORY_POOL_SIZE_IN_MB * MB;
#elif CPU(ARM64)
#if ENABLE(JUMP_ISLANDS)
static constexpr size_t fixedExecutableMemoryPoolSize = 512 * MB;
#else
static constexpr size_t fixedExecutableMemoryPoolSize = 128 * MB;
#endif
#elif CPU(ARM_THUMB2)
#if ENABLE(JUMP_ISLANDS)
static constexpr size_t fixedExecutableMemoryPoolSize = 32 * MB;
#else
static constexpr size_t fixedExecutableMemoryPoolSize = 16 * MB;
#endif
#elif CPU(X86_64)
static constexpr size_t fixedExecutableMemoryPoolSize = 1 * GB;
#else
static constexpr size_t fixedExecutableMemoryPoolSize = 32 * MB;
#endif
#if ENABLE(JUMP_ISLANDS)
#if CPU(ARM64)
static constexpr double islandRegionSizeFraction = 0.125;
static constexpr size_t islandSizeInBytes = 4;
#elif CPU(ARM_THUMB2)
static constexpr double islandRegionSizeFraction = 0.05;
static constexpr size_t islandSizeInBytes = 4;
#endif
#endif
// Quick sanity check, in case FIXED_EXECUTABLE_MEMORY_POOL_SIZE_IN_MB was set.
#if !ENABLE(JUMP_ISLANDS)
static_assert(fixedExecutableMemoryPoolSize <= MacroAssembler::nearJumpRange, "Executable pool size is too large for near jump/call without JUMP_ISLANDS");
#endif
#if CPU(ARM)
static constexpr double executablePoolReservationFraction = 0.15;
#else
static constexpr double executablePoolReservationFraction = 0.25;
#endif
#if ENABLE(LIBPAS_JIT_HEAP)
// This size is derived from jit_config's medium table size.
static constexpr size_t minimumExecutablePoolReservationSize = 256 * KB;
static_assert(fixedExecutableMemoryPoolSize * executablePoolReservationFraction >= minimumExecutablePoolReservationSize);
static_assert(fixedExecutableMemoryPoolSize < 4 * GB, "ExecutableMemoryHandle assumes it is less than 4GB");
#endif
#if HAVE(KDEBUG_H)
// 325696c8-e7cc-11ee-9f4e-325096b39f47
static constexpr WTF::UUID jscJITNamespace { static_cast<UInt128>(0x325696c8e7cc11eeULL) << 64 | (0x9f4e325096b39f47ULL) };
#endif
static bool isJITEnabled()
{
bool jitEnabled = !g_jscConfig.jitDisabled;
#if HAVE(IOS_JIT_RESTRICTIONS)
jitEnabled = jitEnabled && (processHasEntitlement("dynamic-codesigning"_s) || processHasEntitlement("com.apple.developer.cs.allow-jit"_s));
#elif HAVE(MAC_JIT_RESTRICTIONS) && USE(APPLE_INTERNAL_SDK)
jitEnabled = jitEnabled && processHasEntitlement("com.apple.security.cs.allow-jit"_s);
#endif
return jitEnabled;
}
void ExecutableAllocator::disableJIT()
{
ASSERT(!g_jscConfig.fixedVMPoolExecutableAllocator);
if (g_jscConfig.jitDisabled) {
RELEASE_ASSERT(!Options::useJIT());
return;
}
g_jscConfig.jitDisabled = true;
Options::useJIT() = false;
#if HAVE(IOS_JIT_RESTRICTIONS) || HAVE(MAC_JIT_RESTRICTIONS) && USE(APPLE_INTERNAL_SDK)
#if HAVE(IOS_JIT_RESTRICTIONS)
bool shouldDisableJITMemory = processHasEntitlement("dynamic-codesigning"_s) || processHasEntitlement("com.apple.developer.cs.allow-jit"_s);
#else
bool shouldDisableJITMemory = processHasEntitlement("com.apple.security.cs.allow-jit"_s) && !isKernOpenSource();
#endif
if (shouldDisableJITMemory) {
// Because of an OS quirk, even after the JIT region has been unmapped,
// the OS thinks that region is reserved, and as such, can cause Gigacage
// allocation to fail. We work around this by initializing the Gigacage
// first.
// Note: when called, disableJIT() is always called extra early in the
// process bootstrap. Under normal operation (when disableJIT() isn't
// called at all), we will naturally initialize the Gigacage before we
// allocate the JIT region. Hence, this workaround is merely ensuring the
// same behavior of allocation ordering.
Gigacage::ensureGigacage();
constexpr size_t size = 1;
constexpr int protection = PROT_READ | PROT_WRITE | PROT_EXEC;
constexpr int fd = OSAllocator::JSJITCodePages;
int flags = MAP_PRIVATE | MAP_ANON | (Options::useJITCage() ? MAP_EXECUTABLE_FOR_JIT_WITH_JIT_CAGE : MAP_EXECUTABLE_FOR_JIT);
void* allocation = mmap(nullptr, size, protection, flags, fd, 0);
const void* executableMemoryAllocationFailure = reinterpret_cast<void*>(-1);
RELEASE_ASSERT_WITH_MESSAGE(allocation && allocation != executableMemoryAllocationFailure, "We should not have allocated executable memory before disabling the JIT.");
RELEASE_ASSERT_WITH_MESSAGE(!munmap(allocation, size), "Unmapping executable memory should succeed so we do not have any executable memory in the address space");
RELEASE_ASSERT_WITH_MESSAGE(mmap(nullptr, size, protection, flags, fd, 0) == executableMemoryAllocationFailure, "Allocating executable memory should fail after disableJIT() is called.");
}
#endif
}
#if OS(DARWIN) && HAVE(REMAP_JIT)
#if USE(EXECUTE_ONLY_JIT_WRITE_FUNCTION)
static ALWAYS_INLINE MacroAssemblerCodeRef<JITThunkPtrTag> jitWriteThunkGenerator(void* writableAddr, void* stubBase, size_t stubSize)
{
auto exitScope = makeScopeExit([] {
RELEASE_ASSERT(!g_jscConfig.useFastJITPermissions);
});
using namespace ARM64Registers;
using TrustedImm32 = MacroAssembler::TrustedImm32;
MacroAssembler jit;
jit.tagReturnAddress();
jit.move(MacroAssembler::TrustedImmPtr(writableAddr), x7);
jit.addPtr(x7, x0);
jit.move(x0, x3);
MacroAssembler::Jump smallCopy = jit.branch64(MacroAssembler::Below, x2, MacroAssembler::TrustedImm64(64));
jit.add64(TrustedImm32(32), x3);
jit.and64(TrustedImm32(-32), x3);
jit.loadPair64(x1, x12, x13);
jit.loadPair64(x1, TrustedImm32(16), x14, x15);
jit.sub64(x3, x0, x5);
jit.addPtr(x5, x1);
jit.loadPair64(x1, x8, x9);
jit.loadPair64(x1, TrustedImm32(16), x10, x11);
jit.add64(TrustedImm32(32), x1);
jit.sub64(x5, x2);
jit.storePair64(x12, x13, x0);
jit.storePair64(x14, x15, x0, TrustedImm32(16));
MacroAssembler::Jump cleanup = jit.branchSub64(MacroAssembler::BelowOrEqual, TrustedImm32(64), x2);
MacroAssembler::Label copyLoop = jit.label();
jit.storePair64WithNonTemporalAccess(x8, x9, x3);
jit.storePair64WithNonTemporalAccess(x10, x11, x3, TrustedImm32(16));
jit.add64(TrustedImm32(32), x3);
jit.loadPair64WithNonTemporalAccess(x1, x8, x9);
jit.loadPair64WithNonTemporalAccess(x1, TrustedImm32(16), x10, x11);
jit.add64(TrustedImm32(32), x1);
jit.branchSub64(MacroAssembler::Above, TrustedImm32(32), x2).linkTo(copyLoop, &jit);
cleanup.link(&jit);
jit.add64(x2, x1);
jit.loadPair64(x1, x12, x13);
jit.loadPair64(x1, TrustedImm32(16), x14, x15);
jit.storePair64(x8, x9, x3);
jit.storePair64(x10, x11, x3, TrustedImm32(16));
jit.addPtr(x2, x3);
jit.storePair64(x12, x13, x3, TrustedImm32(32));
jit.storePair64(x14, x15, x3, TrustedImm32(48));
jit.ret();
MacroAssembler::Label local0 = jit.label();
jit.load64(MacroAssembler::PostIndexAddress(x1, 8), x6);
jit.store64(x6, MacroAssembler::PostIndexAddress(x3, 8));
smallCopy.link(&jit);
jit.branchSub64(MacroAssembler::AboveOrEqual, TrustedImm32(8), x2).linkTo(local0, &jit);
MacroAssembler::Jump local2 = jit.branchAdd64(MacroAssembler::Equal, TrustedImm32(8), x2);
MacroAssembler::Label local1 = jit.label();
jit.load8(x1, PostIndex(1), x6);
jit.store8(x6, x3, PostIndex(1));
jit.branchSub64(MacroAssembler::NotEqual, TrustedImm32(1), x2).linkTo(local1, &jit);
local2.link(&jit);
jit.ret();
auto stubBaseCodePtr = CodePtr<LinkBufferPtrTag>(tagCodePtr<LinkBufferPtrTag>(stubBase));
LinkBuffer linkBuffer(jit, stubBaseCodePtr, stubSize, LinkBuffer::Profile::Thunk);
// We don't use FINALIZE_CODE() for two reasons.
// The first is that we don't want the writeable address, as disassembled instructions,
// to appear in the console or anywhere in memory, via the PrintStream buffer.
// The second is we can't guarantee that the code is readable when using the
// asyncDisassembly option as our caller will set our pages execute only.
return linkBuffer.finalizeCodeWithoutDisassembly<JITThunkPtrTag>(nullptr);
}
#else // not USE(EXECUTE_ONLY_JIT_WRITE_FUNCTION)
static void genericWriteToJITRegion(off_t offset, const void* data, size_t dataSize)
{
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
memcpy((void*)(g_jscConfig.startOfFixedWritableMemoryPool + offset), data, dataSize);
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
}
static MacroAssemblerCodeRef<JITThunkPtrTag> ALWAYS_INLINE jitWriteThunkGenerator(void* address, void*, size_t)
{
g_jscConfig.startOfFixedWritableMemoryPool = reinterpret_cast<uintptr_t>(address);
void* function = reinterpret_cast<void*>(&genericWriteToJITRegion);
#if CPU(ARM_THUMB2)
// Handle thumb offset
uintptr_t functionAsInt = reinterpret_cast<uintptr_t>(function);
functionAsInt -= 1;
function = reinterpret_cast<void*>(functionAsInt);
#endif
auto codePtr = CodePtr<JITThunkPtrTag>(tagCFunctionPtr<JITThunkPtrTag>(function));
return MacroAssemblerCodeRef<JITThunkPtrTag>::createSelfManagedCodeRef(codePtr);
}
#endif // USE(EXECUTE_ONLY_JIT_WRITE_FUNCTION)
static ALWAYS_INLINE void initializeSeparatedWXHeaps(void* stubBase, size_t stubSize, void* jitBase, size_t jitSize)
{
auto exitScope = makeScopeExit([] {
RELEASE_ASSERT(!g_jscConfig.useFastJITPermissions);
});
mach_vm_address_t writableAddr = 0;
// Create a second mapping of the JIT region at a random address.
vm_prot_t cur, max;
int remapFlags = VM_FLAGS_ANYWHERE;
#if defined(VM_FLAGS_RANDOM_ADDR)
remapFlags |= VM_FLAGS_RANDOM_ADDR;
#endif
kern_return_t ret = mach_vm_remap(mach_task_self(), &writableAddr, jitSize, 0,
remapFlags,
mach_task_self(), (mach_vm_address_t)jitBase, FALSE,
&cur, &max, VM_INHERIT_DEFAULT);
bool remapSucceeded = (ret == KERN_SUCCESS);
if (!remapSucceeded)
return;
// Assemble a thunk that will serve as the means for writing into the JIT region.
MacroAssemblerCodeRef<JITThunkPtrTag> writeThunk = jitWriteThunkGenerator(reinterpret_cast<void*>(writableAddr), stubBase, stubSize);
int result = 0;
#if USE(EXECUTE_ONLY_JIT_WRITE_FUNCTION)
// Prevent reading the write thunk code.
result = vm_protect(mach_task_self(), reinterpret_cast<vm_address_t>(stubBase), stubSize, true, VM_PROT_EXECUTE);
RELEASE_ASSERT(!result);
#endif
// Prevent writing into the executable JIT mapping.
result = vm_protect(mach_task_self(), reinterpret_cast<vm_address_t>(jitBase), jitSize, true, VM_PROT_READ | VM_PROT_EXECUTE);
RELEASE_ASSERT(!result);
// Prevent execution in the writable JIT mapping.
result = vm_protect(mach_task_self(), static_cast<vm_address_t>(writableAddr), jitSize, true, VM_PROT_READ | VM_PROT_WRITE);
RELEASE_ASSERT(!result);
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
// Zero out writableAddr to avoid leaking the address of the writable mapping.
memset_s(&writableAddr, sizeof(writableAddr), 0, sizeof(writableAddr));
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
#if ENABLE(SEPARATED_WX_HEAP)
g_jscConfig.jitWriteSeparateHeaps = reinterpret_cast<JITWriteSeparateHeapsFunction>(writeThunk.code().taggedPtr());
#endif
}
#endif // OS(DARWIN) && HAVE(REMAP_JIT)
struct JITReservation {
PageReservation pageReservation;
void* base { nullptr };
size_t size { 0 };
};
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
static ALWAYS_INLINE JITReservation initializeJITPageReservation()
{
JITReservation reservation;
if (!isJITEnabled())
return reservation;
#if OS(DARWIN)
// Call pageSize() to run its assertions to enforce invariants that executablePageSize() relies on.
WTF::pageSize();
#endif
reservation.size = fixedExecutableMemoryPoolSize;
if (Options::jitMemoryReservationSize()) {
reservation.size = Options::jitMemoryReservationSize();
#if ENABLE(LIBPAS_JIT_HEAP)
if (reservation.size * executablePoolReservationFraction < minimumExecutablePoolReservationSize)
reservation.size += minimumExecutablePoolReservationSize;
#endif
}
reservation.size = std::max(roundUpToMultipleOf(executablePageSize(), reservation.size), executablePageSize() * 2);
#if !ENABLE(JUMP_ISLANDS)
RELEASE_ASSERT(reservation.size <= MacroAssembler::nearJumpRange, "Executable pool size is too large for near jump/call without JUMP_ISLANDS");
#endif
#if ENABLE(LIBPAS_JIT_HEAP)
if (reservation.size < minimumPoolSizeForSegregatedHeap)
jit_heap_runtime_config.max_segregated_object_size = 0;
#endif
auto tryCreatePageReservation = [] (size_t reservationSize) {
#if OS(LINUX)
// On Linux, if we use uncommitted reservation, mmap operation is recorded with small page size in perf command's output.
// This makes the following JIT code logging broken and some of JIT code is not recorded correctly.
// To avoid this problem, we use committed reservation if we need perf JITDump logging.
if (Options::logJITCodeForPerf())
return PageReservation::tryReserveAndCommitWithGuardPages(reservationSize, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true, false);
#endif
if (Options::useJITCage() && JSC_ALLOW_JIT_CAGE_SPECIFIC_RESERVATION)
return PageReservation::tryReserve(reservationSize, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true, Options::useJITCage());
return PageReservation::tryReserveWithGuardPages(reservationSize, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true, false);
};
reservation.pageReservation = tryCreatePageReservation(reservation.size);
if (Options::verboseExecutablePoolAllocation())
dataLog(getpid(), ": Got executable pool reservation at ", RawPointer(reservation.pageReservation.base()), "...", RawPointer(reservation.pageReservation.end()), ", while I'm at ", RawPointer(reinterpret_cast<void*>(initializeJITPageReservation)), "\n");
if (reservation.pageReservation) {
ASSERT(reservation.pageReservation.size() == reservation.size);
reservation.base = reservation.pageReservation.base();
g_jscConfig.useFastJITPermissions = threadSelfRestrictSupported<MemoryRestriction::kRwxToRw>();
if (g_jscConfig.useFastJITPermissions)
threadSelfRestrict<MemoryRestriction::kRwxToRx>();
#if ENABLE(SEPARATED_WX_HEAP)
if (!g_jscConfig.useFastJITPermissions) {
// First page of our JIT allocation is reserved.
ASSERT(reservation.size >= executablePageSize() * 2);
reservation.base = (void*)((uintptr_t)(reservation.base) + executablePageSize());
reservation.size -= executablePageSize();
initializeSeparatedWXHeaps(reservation.pageReservation.base(), executablePageSize(), reservation.base, reservation.size);
}
#endif
void* reservationEnd = static_cast<uint8_t*>(reservation.base) + reservation.size;
g_jscConfig.startExecutableMemory = reservation.base;
g_jscConfig.endExecutableMemory = reservationEnd;
#if !USE(SYSTEM_MALLOC)
static_assert(WebConfig::reservedSlotsForExecutableAllocator >= 2);
WebConfig::g_config[0] = std::bit_cast<uintptr_t>(reservation.base);
WebConfig::g_config[1] = std::bit_cast<uintptr_t>(reservationEnd);
#endif
#if HAVE(KDEBUG_H)
{
uint64_t pid = getCurrentProcessID();
auto uuid = WTF::UUID::createVersion5(jscJITNamespace, std::span { std::bit_cast<const uint8_t*>(&pid), sizeof(pid) });
kdebug_trace(KDBG_CODE(DBG_DYLD, DBG_DYLD_UUID, DBG_DYLD_UUID_MAP_A), WTF::byteSwap64(uuid.high()), WTF::byteSwap64(uuid.low()), std::bit_cast<uintptr_t>(reservation.base), 0);
}
#endif
}
return reservation;
}
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
class FixedVMPoolExecutableAllocator final {
// This does not need to be TZONE_ALLOCATED because it's only used as a singleton
// and is only allocated once long before any scripts are executed.
WTF_MAKE_SEQUESTERED_IMMORTAL_ALLOCATED(FixedVMPoolExecutableAllocator);
#if ENABLE(JUMP_ISLANDS)
class Islands;
class RegionAllocator;
#endif
public:
FixedVMPoolExecutableAllocator()
#if !ENABLE(JUMP_ISLANDS)
: m_allocator(*this)
#endif
{
JITReservation reservation = initializeJITPageReservation();
m_reservation = WTFMove(reservation.pageReservation);
if (m_reservation) {
#if ENABLE(JUMP_ISLANDS)
// Consider this scenario:
//
// <------------- nearJumpRange ------------->
// <------------- nearJumpRange -------------->
// [ island 0 ] [ JIT region 1 ] [ island 1 ] [ JIT region 2 ] [ island 2 ] [ JIT region3 ]
//
// C1 ---jump---> I1 --------------jump---------> I2 ---jump---> C3
//
// In order to jump across a distance that spans multiple nearJumpRanges, we currently
// use chaining near jumps. Hence, a near jump in a jump island also needs to be able
// to reach its neighboring jump islands in order to form this chain.
//
// For example, let say we have code in JIT region 1 that needs to jump to code in JIT region 3 in
// the illustration above. That jump will be implemented as:
// 1. Code C1 in JIT region 1 near jumps to island I1 in island 1.
// 2. Island I1 near jumps to island I2 in island 2.
// 3. Island I2 near jumps to code C3 in JIT region 3.
//
// Each of these near jumps need to be within the range of MacroAssembler::nearJumpRange.
//
// As a result, the maximum size of each JIT region is:
// MacroAssembler::nearJumpRange - 2 * islandRegionSize
//
// This is why each RegionAllocator tracks a range of m_regionSize instead of
// MacroAssembler::nearJumpRange.
//
// Note: the illustration above shows a jump chain in the forward direction. The jump island
// scheme also allows for a jump chain in the backward direction e.g. from C3 to C1.
const size_t islandRegionSize = roundUpToMultipleOf(executablePageSize(), static_cast<size_t>(MacroAssembler::nearJumpRange * islandRegionSizeFraction));
m_regionSize = MacroAssembler::nearJumpRange - islandRegionSize;
RELEASE_ASSERT(isPageAligned(executablePageSize(), islandRegionSize));
RELEASE_ASSERT(isPageAligned(executablePageSize(), m_regionSize));
const unsigned numAllocators = (reservation.size + m_regionSize - 1) / m_regionSize;
m_allocators = FixedVector<RegionAllocator>::createWithSizeAndConstructorArguments(numAllocators, *this);
uintptr_t start = std::bit_cast<uintptr_t>(memoryStart());
uintptr_t reservationEnd = std::bit_cast<uintptr_t>(memoryEnd());
for (size_t i = 0; i < numAllocators; ++i) {
uintptr_t end = start + m_regionSize;
uintptr_t islandBegin = end - islandRegionSize;
// The island in the very last region is never actually used (everything goes backwards), but we
// can't put code there in case they do need to use a backward jump island, so set up accordingly.
if (i == numAllocators - 1)
islandBegin = end = std::min(islandBegin, reservationEnd);
RELEASE_ASSERT(end <= reservationEnd);
m_allocators[i].configure(start, islandBegin, end);
m_bytesReserved += m_allocators[i].allocatorSize();
start += m_regionSize;
}
#else
m_allocator.addFreshFreeSpace(reservation.base, reservation.size);
m_bytesReserved += reservation.size;
#endif
#if ENABLE(MPROTECT_RX_TO_RWX)
ptrdiff_t pagesInReservation = (std::bit_cast<uint8_t*>(g_jscConfig.endExecutableMemory) - std::bit_cast<uint8_t*>(g_jscConfig.startExecutableMemory)) / executablePageSize();
m_pageWriterCounts = std::bit_cast<uint8_t*>(WTF::fastZeroedMalloc(pagesInReservation));
#endif
}
}
~FixedVMPoolExecutableAllocator()
{
m_reservation.deallocate();
}
void* memoryStart() { return g_jscConfig.startExecutableMemory; }
void* memoryEnd() { return g_jscConfig.endExecutableMemory; }
bool isValid() { return !!m_reservation; }
RefPtr<ExecutableMemoryHandle> allocate(size_t sizeInBytes)
{
#if ENABLE(LIBPAS_JIT_HEAP)
Vector<void*, 0> randomAllocations;
if (UNLIKELY(Options::useRandomizingExecutableIslandAllocation())) {
// Let's fragment the executable memory agressively
auto bytesAllocated = m_bytesAllocated.load(std::memory_order_relaxed);
uint64_t allocationRoom = (m_reservation.size() - bytesAllocated) * 1 / 100 / sizeInBytes;
if (!allocationRoom)
allocationRoom = 1;
int count = cryptographicallyRandomNumber<uint32_t>() % allocationRoom;
randomAllocations.resize(count);
for (int i = 0; i < count; ++i) {
void* result = jit_heap_try_allocate(sizeInBytes);
if (!result) {
// We are running out of memory, so make sure this allocation will succeed.
for (int j = 0; j < i; ++j)
jit_heap_deallocate(randomAllocations[j]);
randomAllocations.resize(0);
break;
}
randomAllocations[i] = result;
}
}
auto result = ExecutableMemoryHandle::createImpl(sizeInBytes);
if (LIKELY(result))
m_bytesAllocated.fetch_add(result->sizeInBytes(), std::memory_order_relaxed);
if (UNLIKELY(Options::useRandomizingExecutableIslandAllocation())) {
for (unsigned i = 0; i < randomAllocations.size(); ++i)
jit_heap_deallocate(randomAllocations[i]);
}
return result;
#elif ENABLE(JUMP_ISLANDS)
Locker locker { getLock() };
unsigned start = 0;
if (UNLIKELY(Options::useRandomizingExecutableIslandAllocation()))
start = cryptographicallyRandomNumber<uint32_t>() % m_allocators.size();
unsigned i = start;
while (true) {
RegionAllocator& allocator = m_allocators[i];
if (RefPtr<ExecutableMemoryHandle> result = allocator.allocate(locker, sizeInBytes))
return result;
i = (i + 1) % m_allocators.size();
if (i == start)
break;
}
return nullptr;
#else
return m_allocator.allocate(sizeInBytes);
#endif
}
Lock& getLock() WTF_RETURNS_LOCK(m_lock) { return m_lock; }
#if ENABLE(LIBPAS_JIT_HEAP)
void shrinkBytesAllocated(size_t oldSizeInBytes, size_t newSizeInBytes)
{
m_bytesAllocated.fetch_add(newSizeInBytes - oldSizeInBytes, std::memory_order_relaxed);
}
#endif
// Non atomic
size_t bytesAllocated()
{
#if ENABLE(LIBPAS_JIT_HEAP)
return m_bytesAllocated.load(std::memory_order_relaxed);
#else
size_t result = 0;
forEachAllocator([&] (Allocator& allocator) {
result += allocator.bytesAllocated();
});
return result;
#endif
}
size_t bytesReserved() const
{
return m_bytesReserved;
}
size_t bytesAvailable()
{
size_t bytesReserved = this->bytesReserved();
#if ENABLE(LIBPAS_JIT_HEAP)
size_t nonAvailableSize = static_cast<size_t>(bytesReserved * executablePoolReservationFraction);
if (nonAvailableSize < minimumExecutablePoolReservationSize)
return bytesReserved - minimumExecutablePoolReservationSize;
return bytesReserved - nonAvailableSize;
#else
return static_cast<size_t>(bytesReserved * (1 - executablePoolReservationFraction));
#endif
}
#if !ENABLE(LIBPAS_JIT_HEAP)
size_t bytesCommitted()
{
size_t result = 0;
forEachAllocator([&] (Allocator& allocator) {
result += allocator.bytesCommitted();
});
return result;
}
#endif
bool isInAllocatedMemory(const AbstractLocker& locker, void* address)
{
#if ENABLE(JUMP_ISLANDS)
if (RegionAllocator* allocator = findRegion(std::bit_cast<uintptr_t>(address)))
return allocator->isInAllocatedMemory(locker, address);
return false;
#else
return m_allocator.isInAllocatedMemory(locker, address);
#endif
}
#if ENABLE(META_ALLOCATOR_PROFILE)
void dumpProfile()
{
forEachAllocator([&] (Allocator& allocator) {
allocator.dumpProfile();
});
}
#endif
#if ENABLE(MPROTECT_RX_TO_RWX)
static std::pair<size_t, size_t> pageRangeForWrittenRegion(const void* start, size_t sizeInBytes, size_t pageSize)
{
size_t startPage = std::bit_cast<uintptr_t>(std::bit_cast<uint8_t*>(start) - std::bit_cast<uint8_t*>(g_jscConfig.startExecutableMemory)) / pageSize;
size_t endPage = WTF::roundUpToMultipleOf(pageSize, std::bit_cast<uintptr_t>(start) - std::bit_cast<uintptr_t>(g_jscConfig.startExecutableMemory) + sizeInBytes) / pageSize;
return { startPage, endPage };
}
void startWriting(const void* start, size_t sizeInBytes)
{
size_t pageSize = executablePageSize();
auto [startPage, endPage] = pageRangeForWrittenRegion(start, sizeInBytes, pageSize);
uint8_t* startAddress = std::bit_cast<uint8_t*>(g_jscConfig.startExecutableMemory);
{
Locker locker(m_pageLock);
ssize_t firstFirstWriterPage = -1; // We use this to track runs of pages for which we are the first writer, since this means their mprotect() calls can be batched.
for (size_t i = startPage; i < endPage; i ++) {
if (!(m_pageWriterCounts[i]++)) {
if (firstFirstWriterPage == -1)
firstFirstWriterPage = i;
} else if (firstFirstWriterPage != -1) {
mprotect(startAddress + pageSize * firstFirstWriterPage, (i - firstFirstWriterPage) * pageSize, PROT_READ | PROT_WRITE | PROT_EXEC);
firstFirstWriterPage = -1;
}
}
if (firstFirstWriterPage != -1)
mprotect(startAddress + pageSize * firstFirstWriterPage, (endPage - firstFirstWriterPage) * pageSize, PROT_READ | PROT_WRITE | PROT_EXEC);
}
}
void finishWriting(const void* start, size_t sizeInBytes)
{
size_t pageSize = executablePageSize();
auto [startPage, endPage] = pageRangeForWrittenRegion(start, sizeInBytes, pageSize);
uint8_t* startAddress = std::bit_cast<uint8_t*>(g_jscConfig.startExecutableMemory);
{
Locker locker(m_pageLock);
ssize_t firstLastWriterPage = -1; // We use this to track runs of pages for which we are the last writer, since this means their mprotect() calls can be batched.
for (size_t i = startPage; i < endPage; i ++) {
if (!--m_pageWriterCounts[i]) {
if (firstLastWriterPage == -1)
firstLastWriterPage = i;
} else if (firstLastWriterPage != -1) {
mprotect(startAddress + pageSize * firstLastWriterPage, (i - firstLastWriterPage) * pageSize, PROT_READ | PROT_EXEC);
firstLastWriterPage = -1;
}
}
if (firstLastWriterPage != -1)
mprotect(startAddress + pageSize * firstLastWriterPage, (endPage - firstLastWriterPage) * pageSize, PROT_READ | PROT_EXEC);
}
}
#endif
#if !ENABLE(LIBPAS_JIT_HEAP)
MetaAllocator::Statistics currentStatistics()
{
Locker locker { getLock() };
MetaAllocator::Statistics result { 0, 0, 0 };
forEachAllocator([&] (Allocator& allocator) {
auto allocatorStats = allocator.currentStatistics(locker);
result.bytesAllocated += allocatorStats.bytesAllocated;
result.bytesReserved += allocatorStats.bytesReserved;
result.bytesCommitted += allocatorStats.bytesCommitted;
});
return result;
}
#endif // !ENABLE(LIBPAS_JIT_HEAP)
#if ENABLE(LIBPAS_JIT_HEAP)
void handleWillBeReleased(ExecutableMemoryHandle& handle, size_t sizeInBytes)
{
m_bytesAllocated.fetch_sub(sizeInBytes, std::memory_order_relaxed);
#if ENABLE(JUMP_ISLANDS)
if (m_islandsForJumpSourceLocation.isEmpty())
return;
Locker locker { getLock() };
handleWillBeReleased(locker, handle);
#else // ENABLE(JUMP_ISLANDS) -> so !ENABLE(JUMP_ISLANDS)
UNUSED_PARAM(handle);
#endif // ENABLE(JUMP_ISLANDS) -> so end of !ENABLE(JUMP_ISLANDS)
}
#endif // ENABLE(LIBPAS_JIT_HEAP)
#if ENABLE(JUMP_ISLANDS)
void handleWillBeReleased(const Locker<Lock>& locker, ExecutableMemoryHandle& handle)
{
if (m_islandsForJumpSourceLocation.isEmpty())
return;
Vector<Islands*, 16> toRemove;
void* start = handle.start().untaggedPtr();
void* end = handle.end().untaggedPtr();
m_islandsForJumpSourceLocation.iterate([&] (Islands& islands, bool& visitLeft, bool& visitRight) {
if (start <= islands.key() && islands.key() < end)
toRemove.append(&islands);
if (islands.key() > start)
visitLeft = true;
if (islands.key() < end)
visitRight = true;
});
for (Islands* islands : toRemove)
freeIslands(locker, islands);
if (ASSERT_ENABLED) {
m_islandsForJumpSourceLocation.iterate([&] (Islands& islands, bool& visitLeft, bool& visitRight) {
if (start <= islands.key() && islands.key() < end) {
dataLogLn("did not remove everything!");
RELEASE_ASSERT_NOT_REACHED();
}
visitLeft = true;
visitRight = true;
});
}
}
void* makeIsland(uintptr_t jumpLocation, uintptr_t newTarget, bool concurrently, bool useMemcpy)
{
Locker locker { getLock() };
return islandForJumpLocation(locker, jumpLocation, newTarget, concurrently, useMemcpy);
}
private:
RegionAllocator* findRegion(uintptr_t ptr)
{
RegionAllocator* result = nullptr;
forEachAllocator([&] (RegionAllocator& allocator) {
if (allocator.start() <= ptr && ptr < allocator.end()) {
result = &allocator;
return IterationStatus::Done;
}
return IterationStatus::Continue;
});
return result;
}
void freeJumpIslands(const Locker<Lock>&, Islands* islands)
{
for (CodeLocationLabel<ExecutableMemoryPtrTag> jumpIsland : islands->jumpIslands) {
uintptr_t untaggedJumpIsland = std::bit_cast<uintptr_t>(jumpIsland.dataLocation());
RegionAllocator* allocator = findRegion(untaggedJumpIsland);
RELEASE_ASSERT(allocator);
allocator->freeIsland(untaggedJumpIsland);
}
islands->jumpIslands.clear();
}
void freeIslands(const Locker<Lock>& locker, Islands* islands)
{
freeJumpIslands(locker, islands);
m_islandsForJumpSourceLocation.remove(islands);
delete islands;
}
void* islandForJumpLocation(const Locker<Lock>& locker, uintptr_t jumpLocation, uintptr_t target, bool concurrently, bool useMemcpy)
{
Islands* islands = m_islandsForJumpSourceLocation.findExact(std::bit_cast<void*>(jumpLocation));
if (islands) {
// FIXME: We could create some method of reusing already allocated islands here, but it's
// unlikely to matter in practice.
if (!concurrently)
freeJumpIslands(locker, islands);
} else {
islands = new Islands;
islands->jumpSourceLocation = CodeLocationLabel<ExecutableMemoryPtrTag>(tagCodePtr<ExecutableMemoryPtrTag>(std::bit_cast<void*>(jumpLocation)));
m_islandsForJumpSourceLocation.insert(islands);
}
RegionAllocator* allocator = findRegion(jumpLocation > target ? jumpLocation - m_regionSize : jumpLocation);
RELEASE_ASSERT(allocator);
void* result = allocator->allocateIsland();
void* currentIsland = result;
jumpLocation = std::bit_cast<uintptr_t>(currentIsland);
while (true) {
islands->jumpIslands.append(CodeLocationLabel<ExecutableMemoryPtrTag>(tagCodePtr<ExecutableMemoryPtrTag>(currentIsland)));
auto emitJumpTo = [&] (void* target) {
RELEASE_ASSERT(Assembler::canEmitJump(std::bit_cast<void*>(jumpLocation), target));
if (useMemcpy)
Assembler::fillNearTailCall<MachineCodeCopyMode::Memcpy>(currentIsland, target);
else
Assembler::fillNearTailCall<MachineCodeCopyMode::JITMemcpy>(currentIsland, target);
};
if (Assembler::canEmitJump(std::bit_cast<void*>(jumpLocation), std::bit_cast<void*>(target))) {
emitJumpTo(std::bit_cast<void*>(target));
break;
}
uintptr_t nextIslandRegion;
if (jumpLocation > target)
nextIslandRegion = jumpLocation - m_regionSize;
else
nextIslandRegion = jumpLocation + m_regionSize;
RegionAllocator* allocator = findRegion(nextIslandRegion);
RELEASE_ASSERT(allocator);
void* nextIsland = allocator->allocateIsland();
emitJumpTo(nextIsland);
jumpLocation = std::bit_cast<uintptr_t>(nextIsland);
currentIsland = nextIsland;
}
return result;
}
#endif // ENABLE(JUMP_ISLANDS)
private:
class Allocator
#if !ENABLE(LIBPAS_JIT_HEAP)
: public MetaAllocator
#endif
{
#if !ENABLE(LIBPAS_JIT_HEAP)
using Base = MetaAllocator;
#endif
public:
Allocator(FixedVMPoolExecutableAllocator& allocator)
#if !ENABLE(LIBPAS_JIT_HEAP)
: Base(allocator.getLock(), jitAllocationGranule, executablePageSize()) // round up all allocations to 32 bytes
,
#else
:
#endif
m_fixedAllocator(allocator)
{
}
#if ENABLE(LIBPAS_JIT_HEAP)
void addFreshFreeSpace(void* start, size_t sizeInBytes)
{
RELEASE_ASSERT(!m_start);
RELEASE_ASSERT(!m_end);
m_start = reinterpret_cast<uintptr_t>(start);
m_end = m_start + sizeInBytes;
jit_heap_add_fresh_memory(pas_range_create(m_start, m_end));
}
bool isInAllocatedMemory(const AbstractLocker&, void* address)
{
uintptr_t addressAsInt = reinterpret_cast<uintptr_t>(address);
return addressAsInt >= m_start && addressAsInt < m_end;
}
#endif // ENABLE(LIBPAS_JIT_HEAP)
#if !ENABLE(LIBPAS_JIT_HEAP)
FreeSpacePtr allocateNewSpace(size_t&) override
{
// We're operating in a fixed pool, so new allocation is always prohibited.
return nullptr;
}
void notifyNeedPage(void* page, size_t count) override
{
m_fixedAllocator.m_reservation.commit(page, executablePageSize() * count);
}
void notifyPageIsFree(void* page, size_t count) override
{
m_fixedAllocator.m_reservation.decommit(page, executablePageSize() * count);
}
#endif // !ENABLE(LIBPAS_JIT_HEAP)
FixedVMPoolExecutableAllocator& m_fixedAllocator;
#if ENABLE(LIBPAS_JIT_HEAP)
uintptr_t m_start { 0 };
uintptr_t m_end { 0 };
#endif // ENABLE(LIBPAS_JIT_HEAP)
};
#if ENABLE(JUMP_ISLANDS)
class RegionAllocator final : public Allocator {
using Base = Allocator;
public:
RegionAllocator(FixedVMPoolExecutableAllocator& allocator)
: Base(allocator)
{
RELEASE_ASSERT(!(executablePageSize() % islandSizeInBytes), "Current implementation relies on this");
}
void configure(uintptr_t start, uintptr_t islandBegin, uintptr_t end)
{
RELEASE_ASSERT(start < islandBegin);
RELEASE_ASSERT(islandBegin <= end);
m_start = std::bit_cast<void*>(start);
m_islandBegin = std::bit_cast<void*>(islandBegin);
m_end = std::bit_cast<void*>(end);
RELEASE_ASSERT(!((this->islandBegin() - this->start()) % executablePageSize()));
RELEASE_ASSERT(!((this->end() - this->islandBegin()) % executablePageSize()));
addFreshFreeSpace(std::bit_cast<void*>(this->start()), allocatorSize());
}
// ------------------------------------
// | jit allocations --> <-- islands |
// -------------------------------------
uintptr_t start() { return reinterpret_cast<uintptr_t>(m_start); }
uintptr_t islandBegin() { return reinterpret_cast<uintptr_t>(m_islandBegin); }
uintptr_t end() { return reinterpret_cast<uintptr_t>(m_end); }
size_t maxIslandsInThisRegion() { return (end() - islandBegin()) / islandSizeInBytes; }
uintptr_t allocatorSize()
{
return islandBegin() - start();
}
size_t islandsPerPage()
{
size_t islandsPerPage = executablePageSize() / islandSizeInBytes;
ASSERT(islandsPerPage * islandSizeInBytes == executablePageSize());
ASSERT(isPowerOfTwo(islandsPerPage));
return islandsPerPage;
}
#if !ENABLE(LIBPAS_JIT_HEAP)
void release(const Locker<Lock>& locker, MetaAllocatorHandle& handle) final
{
AssemblyCommentRegistry::singleton().unregisterCodeRange(handle.start().untaggedPtr(), handle.end().untaggedPtr());
m_fixedAllocator.handleWillBeReleased(locker, handle);
Base::release(locker, handle);
}
#endif
void* allocateIsland()
{
uintptr_t end = this->end();
auto findResult = [&] () -> void* {